In the article Urban light pollution: why we're all living with permanent 'mini jetlag'(The Guardian) Ellie Violet Bramley writes about studies that have shown that exposure to light after dusk is quite literally
unnatural, and may be detrimental to health. Astronomer Dr Jason Pun of the Hong Kong University department of physics has been studying light pollution and has done several studies on the subject. Recently they set up 18 stations around Hong Kong stretching from commercial urban sector to residential neighborhoods and on to rural areas. When they compared the levels of light to the standard (meaning how bright the sky would be without artificial lights), they found that the lit areas were about a 1000 times brighter.
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| Hong Kong Skyline By Barry Chum (Own work) [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons |
According to Dr. Pun, “Similar studies in major capitals like Berlin and Vienna, would find something more of the order of 100 to 200 times brighter.”
Most cities like Hong Kong, New York, Tokyo and Las Vegas may be proud of their super bright nightscapes and get many visitors who come to see these illuminated cities. But these brightly lit skies may also be causing health problems. Steven Lockley, a neuroscientist and an associate professor of medicine at Harvard Medical School has been studying the effect of light on alertness, sleep, melatonin levels and its overall impact on human physiology.
Lockley calls any light after dusk as unnatural, he says that with any such exposure "our daytime physiology is triggered and our brains become more alert, our heart rates go up, as does our temperature, and production of the hormone melatonin is suppressed".
The article also mentions Ken Wright at the University of Colorado in Boulder who conducted studies on camping. He found that for campers midnight meant middle of the night, whereas in urban areas the constant presence of light prolongs the daytime, thus leading people living in cities to stay awake longer, sleep later and hence sleep less. This could be causing health problems not yet clearly documented.
Lockley raises a thought-provoking question; "As a society we need to think, do we really need some of these amenities that are putting light pollution into the environment?" adding "Do we need 24/7 garages, do we need 24/7 supermarkets, do we need 24/7 TV? It was only in 1997 that the BBC turned off and there was the national anthem and we all went to bed."
Here are some excerpts of Ellie's article;
The International Dark Sky Association is an organisation of astronomers that aims to teach how to preserve the night sky. Member Scott Kardel says he believes in balance: “While we need certain amounts of light at night for safety, commerce and more, we also need to be more careful about how much light we use, where we use it and for how long.”
But at a more abstract level, Kardel also believes that “having bright skies takes something away from us. All of our ancestors had star-filled skies that inspired countless people in art, literature, religion, science and philosophy.”
It might not be plausible to put the metropolis to bed at dusk, but cities can mitigate some of the worst light pollution. “Proper outdoor lighting,” says Kardel, “conserves energy, reduces glare” and cuts back on so-called light trespass, for example when your neighbour’s bedroom light bleeds into your sitting room.
Lockley thinks LEDS are the “problem, but also the solution: they allow much more sophisticated lighting systems.” The blueness can be fixed, he says. “It is possible to create LED light with multiple colours – you can alter the colours for the right time of day and the right application.”
“We might not quite be at the point where cities are putting in those types of tuneable street lamps,” he adds. But many communities in the UK have either adopted or trialled “part night lighting”, switching off the lights where they’re not needed or lowering illumination levels for part of the night. Motion-sensing technologies are being tested in the Netherlands and Ireland.
At the centre of this shift is a change in the attitudes of city residents and their governments. In Hong Kong, until only a few years ago the government avoided even using the term “light pollution”, says Pun. “They wouldn’t even admit such a thing exists. If you call it something else, like ‘light nuisance’, then I guess it will make life a little easier. Even though it seems like a gloomy situation, no pun intended, I do see a change of mindset.”
In the end the article has some wonderful tips on how to reduce light pollution.
It’s an obvious one, but switch off any lights you are not using.
• Ensure indoor and outdoor lighting is directed at what you’re trying to light and that it’s shaded. Table and floor lamps are better for this than overhead lights.
• Use low-watt lightbulbs – you’ll save on bills and reduce glare.
• Install dimmer switches so you can alter brightness to suit ambient light.
• Use motion sensors or timers so outdoor lights are only on when they need to be.
• Install thick curtains or blinds to minimise light escaping your home at night.
• Ask your local councillor to get street lamps fitted with directional, low energy lights – after all, residential areas don’t need to be lit up like football pitches 24 hours a day.
References:
Urban light pollution: why we're all living with permanent 'mini jetlag' (The Guardian- Oct 23rd 2014)
